Once a single cram system reaches 500 materials (very doable in fact)
It can fuse the first material with Another material.
As an example, a cannon with 500 frag material can fuse with for example kinetic material to form a Shell that splits into high ap frags etc.

having two types of materials at 500 yields the ability to fuse 3 materials and so forth.

Effects:

500 materials
Kinetic/HE = way Faster HE Shells that are armor penetrating
Kinetic/frag = way faster frag Shells that hurl out larger frags in the form of kinetic cram Shells at 15x less caliber than the original Shell upon impact and each lesser Shell has a higher ap.
kinetic/EMP = way faster and armor penetrating

HE/frag = meteor shower style Shells that explode into lesser HE Shells at a set proximity.
HE/EMP = Shells gain a massive explosive radius that sends emp surges into vehicles that are caught in the blast.

frag/EMP = Impacting Shells replace the frags with Lightning surges similar to that of what comes out of PAC's which inflict both emp and kinetic damage.

Kinetic/frag/HE/EMP = Overdrives to fire a much larger Shell with a canon inside it that launches a Shell of original caliber with all original separate material effects at 10 times your cannons oringinal firing rate.

This means this monster can fly through the air and fire 2m Shells almost every second with Frag,HE and EMP maxed in each Shell for that caliber.

It increases your reload time by the double but does not affect the original reload time so the Shell cannon will not be affected.

Sounds like a good idea, but maybe a bit too overpowered and hard to implement. 1500 materials definitely needs changed. Maybe just grants 4x the normal damage, and has some of the effects of the 1000 materials.